Knife sharpener for cutting machine



July 19, 1960 J. 1B. GuRY, JR 2,945,332 KNIFE SHARPENER FOR- CUTTINGMACHINE Filed Sept. 17. 1958' r; I FIG. 3

' INVENTOR.

JOHN B. GURY, JR. FIG. 2 BY ATTORNEYS KNIFE SHARPENER FOR CUTTINGMACHINE John B. Gury, Jr., 1229 Arch Terrace,

Richmond Heights 17, Mo.

Filed Sept. 17, 1958, Ser. No. 761,626

6Claims. ((151-246) The present invention relates generally to machinesfor cutting multiple layers of cloth, and more particularly toimprovements in knife sharpeners for cloth cutters of reciprocatingknife type.

The invention has to do with cloth cutters and knife sharpeners of thekind illustrated and described in applicants Patent No. 2,737,763 ofMarch 13, :1956, and provides certain improvements in the sharpeningdevice disclosed in that patent. Such sharpeners employ a pair ofabrasive belts having their active flights extending in crossedrelationship so as to produce the desired bevel and edge on the oppositeside portions of the blade.

It is an important object of this invention to provide means in theknife sharpening assembly which causes adjacent inner edges of the beltsto apply the more effective grinding action to the knife, and thereforeafford an accurate true knife edge having the optimum keenness. Animportant object is achieved by the provision of means for twisting thecrossed belts in a manner so that the closest edges of the belts areurged against opposite sides of the knife with a pressuregreater thanthe other edges of the belts for best grinding action.

Other advantages are realized by the preceding structural arrangement inthat it closely approaches the optimum condition wherein the belts aredirectly opposite each other, but cannot be attained because the beltsactually cross each other.

Another important objective is realized in that 'the idler nited StatesPatent pulleys of the knife sharpening assembly are provided with meansthat engage a vertical element disposed between such pulleys so as tocant the pulleys in the same direction from the'vertical in order toapply effective pressurebetween the knife and particular edges of thebelts, whereby to provide the advantageous function which was discussedpreviously.

Still another important object is achieved by making the flanges of theidler pulleys of a specific dimensional relationship and by arrangingthe pulleys so that the flanges engage a vertical element disposedtherebetween, whereby to provide the twisting elfect of the beltspreviously discussed.

The foregoing and numerous other objects and advantages of the inventionwill more clearly appear from the following detailed description of apreferred embodiment, particularly when considered in connection withthe accompanying drawing, in which:

Fig. l is a side view of a cutting machine equipped with a sharpeningdevice in accordance with this invention;

Fig. 2 is an enlargedtop elevational view, partly in cross section, ofthe knife sharpening mechanism as. seen along line 22 of Fig. 1;

Fig. 3 is an end view of the knife and knife sharpening assembly as seenfrom line 3-3 of Fig. 2, and

Fig. 4 is a diagrammatic view of the knife and abrasive belts.

Referring now by characters of reference to the drawings, and first toFig. 1, the cutting machine to which this invention applies may be ofany suitable type having a base 10 supporting a standard or pedestal11in which a knife 12 is mounted to reciprocate vertically. A motor 13is operatively connected toknife 12 by a mechanism such as thatillustrated and described in applicants Patent No. 2,737,763 issuedMarch 13, 1956. This connecting mechanism is enclosed within housing 15.

A handle 16 is usually attached to the standard 11 whereby the machinemay be manipulated during the cutting operation.

' According to this invention, a frame and housing 17 is secured tohousing 15 and hence connected to the motor 13. A grinder carriage 20depends from and is supported by mechanism withinhousing 17. The grindercarriage 20 is mounted and guided in its up and down movements in anysuitable or desired manner, for example as disclosed in applicantsPatent No. 2,737,763 issued March 13, 1956. 1

For example, a pair of screws 21 are driven in opposite directions by adrive connection disclosed in the above mentioned patent, and serve tomove the grinder carriage 20 up and down along the knife 12. A drivingWheel 22 which may be provided with a tire 23 of rubber or the like toprovide a frictional driving surface operatively innerconnects with themotor 13, and operatively innerconnects with the screws 21 to rotate andhence reciprocate said carriage 20, all in a manner disclosed in theabove mentioned prior patent. Again, this mechanism is not shown in anydetail since it is not directly involved in this invention.

Extending downwardly from the carrier 20 is a sleeve 24. Mounted torotate on sleeve 24 is a drive pulley 25.

'Journalled within sleeve 24 is a vertical spindle 26 having secured tothe lower end thereof a drive pulley 27 similar to pulley 25. Theparticular mounting of drive pulleys 25 and 27 and their operativelyconnection with screws 21 is as disclosed in the aforesaid Patent No.2,737,763. It is seen that the drive pulleys 25 and 27 are located oneimmediately above the other and mounted for rotation on a commonvertical axis. These drive pulleys 25 and 27 are driven in oppositedirections of rotation. Because the carriage 20 is supported on thescrews 21, it will move up and down with those screws.

Referring now to Fig. 2, fixed on carriage portion 30 depending fromcarriage '20 in front of drive pulleys 25 and 27 is a leaf spring 31.This spring 31 is mounted on a level with the drive pulley 25 andextends outwardly therefrom as is shown in Figs. 1 and 2. Mounted on theleaf spring 31 is a bearing bracket 32 having a shaft portion 33 bentinto C-form as shown in Fig. 2 and slipped over the leaf spring 31. Thebracket 32 is thus movable along the leaf spring 31. A coil spring 34 isconnected to a pin 35 on the leaf spring 31 and to the tab 36 formed onthe shank portion 33. The coil spring 34 therefore tends to urge thebearing bracket 32 outwardly away from the drive pulley 25. The bracketis provided with a forked end, as is shown in Figs. 2 and 3, and isequipped with bearings 37 in which an idler pulley 49 is journalled. Theleaf spring 31 and bracket 32 constitute a resilient arm. An abrasivebelt 41 is arranged to run on the pair of pulleys 25 and 40.

A similar structure provides for a similar sharpening belt '46 to run onthe drive pulley 27. For example, a leaf spring 42 is fixed to theopposite side of carriage portion 30. A bearing bracket 43, similarin'all respects to the bearing bracket 32, is similarly mounted on theleaf spring '42 with a coil spring 44- urging it outwardly from thedrive pulley 27. The leaf spring 42 and bracket 43 constitutes aresilient arm. The bracket 43 carries an idler pulley 45, and sharpeningbelt 46 rides on the two pulleys 27 and 45.

As may be seen from Figs. 2 and 3, these belts 41 s3 and 46 are solocated as to pass one on each side of the knife blade 12. The belts areurged with pressure against the blade while the coil springs 34 and 44provide tension in the belts. As the :entire sharpening, apparatus iscarried by the carriage20, it moves up and .down along the blade inresponse to the movement of'the screws 21. The knife sharpeningapparatus is provided with means for twisting the belts 41 and 46 sothat the adjacent inner edges 47 bear against the'knife edgewith agreater. pres.- sure, as indicatedby force vectorsin Fig. 4, than theouter edges 48. This action enables the more effective grinding by belts41 and 46 tooccur in immediately adjacent zones, and closely aproximatesthe optimum action whereby the belts would :be locateddirectly oppositeeach other. This grinding action provides an accurate keen edge on theblade 12 without any burrs.

To accomplish this result, the upper flange 50 of idler pulley 40 is ofgreater diameter than the lower flange 51, as is best shown in Fig. 3.Similarly, the lower flange 52 of idler, pulley 45 is of greaterdiameter than the upper flange 53. The flanges 50-53, and hence idlerpulleys 40 and 45, ride on the knife guide'll, and because of theirparticular structural relationship, the idler pulleys 40 and 4-5 aretilted from the vertical in the same direction, whereby to twist theabrasive belts 41 and 46. Because the belts 41 and 46 are flexible theentire width of the belts is urged against the'knife edge. However,because of the twisting action alforded by the canted relationship ofidler pulleys 40 and 45, a greater pressure is exerted by the inneredges 47 of the belts against the knife edge than the pressure exertedby the outer edges 48, as previously discussed.

A pressure foot 54 is mounted on the lower end of a shank 55 verticallyslidable within housing 17 and along the carriage 20 and carriageportion 30. As well understood in the art, .the pressure foot 54 isadjustable to different elevations suited to dilferent layers ofmaterial to be cut.

Although the invention has been described by making detailed referenceto a single preferred embodiment, such detail is to be understood in aninstructive, rather than in any restrictive sense, many variants beingpossible within the scope of the claims hereunto appended.

I claim as my invention:

l. A knife sharpening-mechanismfor cutting machines having a knifeguided for reciprocal movement, a grinder carriage movable up and downalong said knife, a pair of driving pulleys mounted on said carriage forrotation on a common vertical axis, the driving pulleys being locatedone immediately above the other, a spring arm supported on said carriageopposite each said driving pulley to' extend outwardly therefrom, anidler pulley mountedon each spring arm, a sharpening belt on each pairof said driving and idler pulleys, said belts having adjacent inneredges and opposite outer edges, said idler pulleys being disposed onopposite sides of the knife and being disposed one above the other, saidspring arms being set to bias said belts for pressure against the knife,each said idler pulley having opposed annular flanges, the top idlerpulley having its upper flange and vertical means between said idlerpulleys engaging said flanges so as to tilt said idler pulleys from thevertical so that adjacent inner edges of said belts are urged againstsaid knife with a pressure greater than the outeredges of said belts.

2. A knife sharpening mechanism for cutting machines having a knifeguided for reciprocal movement, a grinder carriage movable up and downalong said knife, a pair of driving pulleys mounted on said carriageforrotation on a common vertical axis, an idler pulley supported on saidcarriage opposite each, of said driving pulleys, a sharpening belt oneach pair of said driving and idler pulleys, said belts have adjacentinner edges and opposite outer edges, said idler pulleys being disposedon opposite sides of the knife, and means slidably engaging said idlerpulleys to tilt said idler pulleys from the vertical in same directionsothat the adjacent inner edges'of said belts areu'rgeaagainstsaidknifewith a pressure greater than the outer edges of the said belts.

3. A knife sharpening mechanism for cutting machines having a knife,guided for-reciprocal movement, a grinder carriage movable up and downalong said knife, a pair of driving pulleys mountedionirsaid carriagefor rotation on a common vertical axis, an idler pulley supported onsaid carriage opposite of each said driving pulleys, a sharpening belton each pair of said driving and idler pulleys, said'beltsihaving'adjacentinneriedges and opposite outer edges,

saidliidleripulleysIbeing disposed on opposite sides of the knife, eachof said idler pulleys having opposed annular flanges, one flange of eachidler pulley being of greater diameter than .the otl'lerfflange, and:means engaging said flanges of each idler pulley so as to tilt saidpulleys from the vertical so that adjacent inner edges of said belts areurged against said knife with the pressure greater'than the outeredgesof said belts.

4. The combination and arrangement of elements as recited above in claim3, but further characterized in that the said means engaging the idlerpulley flanges includes a vertical element disposed between said idlerpulleys.

. 5. A knife sharpening mechanism for cutting machine having a knifeguided for reciprocal movement, a grinder carriage movable'up and downalong said knife, a pair of driving pulleys mounted on said carriage forrotation on a common vertical axis, an arm supported on said carriageopposite each said driving pulley to extend outwardly therefrom, anidlerpulley-mounted on each arm, a sharpenin'g belt on each-pair of saiddriving and idler pulleys, said idler pulleys being disposed on oppositesides of the knife, saidarms'beingset to bias said belts for pressure"against the -'knife,the belts including adjacent inner edges and outer.opposite edges, a vertical element disposed between said idler pulleys,and means on each idler pulley engaging the vertical element to tilt theidler pulleys from the vertical.

6. A knife sharpening mechanism for cutting machine havingaJknife'gu'ided for reciprocal movement, a grinder carriagemovableup'and down along said knife, a pair of driving pulleys mounted on saidcarriage forrotation on a common vertical'axis, and arms supported onsaid car.- riageoppositeeach'said driving pulley to extend outwardlytherefrom, an idler pulley mountedon each arm, a sharpening belt on eachpair of said driving and idler pulleys, said idler pulleys beingdisposed on opposite sides of the *knife, said arms being set to biassaid belts for pressure against the knife, the'belts including adjacentinner edges "and outer oppositeedges, a vertical element disposedbetween said idler pulleys, each said idler pulley being provided withopposed annular flanges, one flange of each idler pulley beingof greaterdiameter than the other flange, the flanges'of said idler'pulleysengaging the vertical element to tilt the idlerpulleys from thevertical.

References Cited' in'the file of this patent UNITED STATES PATENTS650,004 Brinkman May 22, 1900 2,737,763 I Mar. 13, 1956

